Temperature stable tubular element for inductive devices



Sept. 26, 1967 R. 1.. HATTON 3,344,384

TEMPERATURE STABLE TUBULAR ELEMENT FOR INDUCTIVE DEVICES Filed May 5,.1965 INVENTOR.

RICHARD l HATTON. BY-

ATT'YS United States Patent 3,344,384 TEMPERATURE STABLE TUBULAR ELEMENTFOR INDUCTIVE DEVICES Richard L. Hatton, Elmhurst, Ill., assignor toResinite Corporation, Wheeling, Ill. Filed May 5, 1965, Ser. No. 453,4234 Claims. (Cl. 336-179) This invention relates to a tubular element and,more particularly, to a sleeve-like member useful in connection withelectronic gear as an inductance.

The problem of dimensional stability under varying temperatures isparticularly acute in electronic instruments, especially inductanceswhose value is determined by their dimensions. Since these elements areused in large quantity, it is important that they be constructed aseconomically as possible. In the past, these two objectives; qualityperformance and economical manufacture have not been achieved. Theprovision of the portion of an inductor which achieves these twinobjectives thus constitutes a specific objective of the invention.

A more generalized object of the invention is to provide a thermallystable tubular element which is adapted for use in a variety ofinstallations where ambient temperatures vary such as the voice coil ofa speaker.

A more specific object of the invention is to provide a thermally stablesleeve constructed of spirally wound layers of metal foil ribbons andethylene terephthalate ribbons which is resilient and which ischaracterized by dimensional stability in operation as an inductor partso as to minimize frequency drift.

Other objects and advantages of the invention may be seen in the detailsof construction and operation set down in this specification.

The invention is described in conjunction with an illustrativeembodiment of the accompanying drawing, in which:

FIG. 1 is a perspective view, partially broken away, of a channelselector element of a television set;

FIG. 2 is an enlarged fragmentary perspective view of one of the channelcoils or inductances provided as part of the channel selector of FIG. 1;

FIG. 3 is a perspective view of the inventive sleeve shown with a tuningscrew partially received therein;

FIG. 4 is a fragmentary perspective view of a tube embodying theteachings of the invention and in an intermediate stage of manufacture;

FIG. 5 is a view similar to FIG. 4 but on an enlarged scale and showingthe inventive tube at a subsequent, but still intermediate stage ofmanufacture;

FIG. 6 is a perspective view of the inventive tube in its completed formand prior to insertion in the tuning coil form of FIG. 2;

FIG. 7 is an enlarged end view of the construction seen in FIG. 6;

FIG. 8 is a fragmentary sectional view such as would be seen along thesight line 8-8 applied to FIG. 6; and

FIG. 9 is an exploded perspective view of the invention used in aslightly different operating environment.

In the illustration given and with particular reference to FIG. 1, thenumeral 10 designates generally a channel selector element of atelevision set and includes a U- shaped frame 11 equipped with front andrear upstanding walls 12 and 13, respectively. Rotatably mounted in theframe 11, by virtue of extending through the front rear walls, is ashaft 14 having fixed thereto turret plates 15 and 16. Each of theplates 15 and 16 is notched so as to receive a plurality of tuning coilssuch as is exemplified by the numeral 17. For this purpose, each tuningcoil 17 is equipped with a plurality of windings (see FIG. 2) wheredifferent windings are designated 3,344,384 Patented Sept. 26, 1967 19operating through a gear linkage 20, effective to ad vance or retractthe tuning screw 18. Thus, the inductance of the tuning coil 17 is thusvaried by the degree to which the tuning screw 18 is advanced orretracted within the hollow interior of the coil 17.

The invention here has to do with the sleeve-like member 21 which isinserted within the bore of the tuning coil 17 and which threadablyreceives the tuning screw 18 (see FIG. 3). The sleeve 21 is adhesivelymounted within the bore by means of a polyester coating adhesive.

In television sets, it is necessary for the tuning elements towithstand, without dimensional deformation, temperatures of the order of-90 C. Heretofore, the female thread-providing elements have not beendimensionally stable so that the tuning screw 18 has had the tendencynot to remain anchored properly in place, and thus, destroy the preset,fine tuning.

I find that this undesirable situation can be avoided through a uniquelyconstructed sleeve and the character of the sleeve construction can bemost readily appreciated from a consideration of FIG. 8.

The, tube fragment 21 in FIG. 8 is seen to include as an innermost layera relatively thick layer 22 of ethylene terephthalate. Proceedingoutwardly from the layer 22, I provide a first layer of metal foil 23 ofthe order of 0.00075-0.00125" which advantageously may be ofelectrolytic copper. Thereafter, a similar thickness or second layer ofmetal foil 24 is provided after which I provide two layers 25 and 26 ofethylene terephthalate. Each of the layers is spirally wound relative tothe axis of the tubular element 21 and are adhesively united by means ofa polyester coating adhesive such as Type A of National Bronze PowderCo. A greater or lesser number of layers may be used, depending upon theinstallation, but it is advantageous to sandwich the spirally woundmetal layer between outer layers of spirally wound ethyleneterephthalate. For the particular application involved, the layersidentified in FIG. 8 have the following thicknesses.

i; Element: Thickness, inch 22 0.005 23 0.001 24 0.001 25 0.003 26 0.001

The construction thus described is initially provided in the form of anelongated tube such as is designated 27 in FIG. 4. Depending upon theparticular winding equipment used, the length of the tube 27 may beupwards of several feet in length. Thereafter, a transverse severingoperation is performed such as is indicated schematically by the arrows28 applied to FIG. 4 and which results in the intermediate tubedesignated 29 and seen in enlarged form (relative to FIG. 4) in FIG. 5.Thereafter, I subject the tube 29 to an indenting operation to providethree rows of indentations or recesses 30 in the sidewall of the tube 29to result in the final construction seen in FIGS. 6 and 7.

In operation, the tubular element 21 is slidably inserted Within thehollow core of the tuning coil element 17 after which the tuning screw18 is threadably received therein. The indentations 30 yield against theadvance of the threads provided on the metal screw 18 so that the screw18 may be bottomed as against the shoulder 17c (see FIG. 2) withoutdamage to the element 21. Further, the tuning screw 18 may be retracteduntil it abuts the end wall 11 and continued rotation of the hollowshaft 19 permits the tuning screw 18 to be continually rotated againwithout damage to the sleeve 21. The provision for continued rotation ofthe tuning screw 18 in either direction is necessary since televisionsets are often operated by children who would continue turning a knobeven though a stop has been reached. This safeguard can be realizedWithout stripping the threads in the female thread-providing member andfurther while maintaining the desirable dimensional stability withtemperature change-as would occur between the time a set is first turnedon and after it has been in operation for several minutes, or hours.

I find that through the use of the inventive element, it is unnecessaryto go to expensive and carefully wrought tuning screws 18--for example,relatively inexpensive aluminum screws may be used in place of thepreviously employed brass screws.

A variety of metal foil ribbon may be employed for the development ofthe intermediate layer or layers in the element 21 such as nickelsilver, electrolytic copper as previously mentioned, and cartridgebrass.

In FIG. 9, the numeral 121 designates the inventive tube which isembossed with thread-like depressions at 130. Received within thelaminated tube 121 is a ferrite core 118. The tube 118 is press fittedwithin a metal body 117 which is equipped with a cooperative cap portion117a. Housed Within the body 117 and cover portion 117a is a coil 117bmounted on a flange-equipped bobbin 117C. The entire assemblyconstitutes a shielded transformer with leads as at 117d and 1170 foruse in communications equipmentthe sleeve 121 providing a sure mountingfor the core 118.

While in the foregoing specification, a detailed description of anembodiment of the invention has been set down for the purpose ofillustration, many variations in the details herein given may be made bythose skilled in the art without departing from the spirit and scope ofthe invention.

I claim:

1. A temperature stable tubular element suitable as a component of aninductance comprising inner, intermediate, and outer layers of spirallyarranged adhesively united ribbons, each layer including at least oneribbon spirally wound relative to the tubular element axis, said innerand outer layers being constructed of ethylene terephthalate, saidintermediate layer being constructed of a metal foil, and amale-threaded part positionably received within said element for varyingsaid inductance.

2. The structure of claim 1 in which said element is equipped with aplurality of axially spaced indentations to position said male-threadedpart.

3. The structure of claim 1 in which said intermediate layer isconstructed of copper foil.

4. The structure of claim 1 in which said intermediate layer includes aplurality of metal foils spirally wound and of a total thickness lessthan the thickness of the inner and outer layers.

References Cited UNITED STATES PATENTS 3,130,256 4/1964 Mildner 174107 X3,233,036 2/1966 Jachimowi-cz 174-120 X FOREIGN PATENTS 886,888 1/1962Great Britain.

LEWIS H. MYERS, Primary Examiner.

C. TORRES, T. I. KOZMA, Assistant Examiners.

1. A TEMPERATURE STABLE TUBULAR ELEMENT SUITABLE AS A COMPONENT OF ANINDUCTANCE COMPRISING INNER, INTERMEDIATE, AND OUTER LAYERS OF SPIRALLYARRANGED ADHESIVELY UNITED RIBBONS, EACH LAYER INCLUDING AT LEAST ONERIBBON SPIRALLY WOUND RELATIVE TO THE TUBULAR ELEMENT AXIS, SAID INNERAND OUTER LAYERS BEING CONSTRUCTED OF ETHYLENE TEREPHTHALATE, SAIDINTERMEDIATE LAYER BEING CONSTRUCTED OF A METAL FOIL, AND AMALE-THREADED PART POSITIONABLY RECEIVED WITHIN SAID ELEMENT FOR VARYINGSAID INDUCTANCE.